The present invention relates to an eye examination apparatus including a tonometer for measuring the intraocular pressure of a subject's eye. The invention is especially useful when embodied in an accessory to be attached to existing eye examination apparatus, such as the Goldmann Applanation Tonometer, and is therefore described below with respect to this application.
One of the most common eye examinations carried out by ophthalmologists is an intraocular pressure test. This test is commonly performed on a slit lamp type apparatus equipped with a tonometer unit. The slit lamp comprises a microscope eyepiece carried forwardly of the apparatus to enable an examiner to view a subject's eye located rearwardly of the eyepiece, and a control lever for controlling the position of the eyepiece. The tonometer unit is located rearwardly of the eyepiece and includes a housing, a prism-type contact element to contact the cornea of the subject's eye, and adjusting means including a control knob for varying the pressure applied by the contact element against the subject's eye.
The intraocular pressure test is itself a relatively simple test, but frequently becomes quite complicated, awkward and time-consuming because of the need to adjust both the control lever and the adjusting knob on the tonometer unit at different times during the course of the test. Thus, during one stage, the examiner has to use the fingers of one hand to spread apart the subject's eyelids, and to use the other hand for manipulating both the control lever to control the position of the microscope eyepiece and the control knob on the tonometer unit to adjust the pressure applied to the subject's eye by moving that hand back and forth between the control lever and the control knob.
The existing apparatus makes it very difficult and awkward for the examiner to make the required adjustments in the tonometer and/or in the control lever of the slit lamp without lifting his eyes from the eyepiece, and thereby interrupting visual contact with the subject's eye during these adjustments. Thus, the examiner frequently has to lift his eyes from the eyepiece in order to make an adjustment particularly of the tonometer; but before he resumes viewing through the eyepiece after the adjustment is made, the subject may have moved his eye under examination even slightly. If this should occur, many of the steps of the test, and sometimes the complete test, would have to be repeated. This not only makes the test time-consuming and difficult for the examiner to perform, but also increases the chance of irritating and damaging the subject's eye.
It would therefore be desirable to provide apparatus of the foregoing type which permits the tonometer unit to be adjusted without requiring the examiner to lift his eyes from the eyepiece or his hand from the slit lamp control lever.